Centralized traffic control system



June 1, 1937. I R. M. PHlNNE Y 2,082,740

' CENTRALIZED TRAFFIC CONTROL SYSTEM Filed April 14, 1930 s Sheets-Sheet 1 Q ATTORNEY June 1, 1937. p m 2,082,740

CENTRALIZED TRAFFIC CONTROL SYSTEM Filed April 14, 1930 3 Sheets-Sheet 2 INVENTOR WM W MATTORNEY June 1, 1937. R. M. PHl-NNEY 2,082,740

CENTRALIZED TRAFFIC CONTROL SYSTEM Filed April 14, 1930 s Sheets-Sheet s EN Wm i ON w m 3 N ON mmdmnwZ Patented June I 1937 PATENT OFFICE OENTRALIZED TRAFFIC CONTROL SYSTEM Robert M. Phinney, Rochester, N. Y., assignor to General Railway Signal Company, Rochester,

Application April 14, 1930, Serial No. 444,146

31 Claims.

This invention relates to centralized trafiic con-- trolling systems, and more particularly to such a system of the synchronous selector type employing cycles of impulses having distinctive starting characteristics.

Generally speaking the present invention is an improvement of the general system shown in the prior joint application of R. C. Leake and R. M.

Phinney, Ser. No. 385,740, filed August 14, 1929,

and contemplates the use of interconnecting circuits which make the system more positive in its operation, more economical and more reliable.

In the system of the prior application, each cycle of operation, insofar as the stepping operation is concerned, is exactly the same; for this reason a stepping relay is actuated at every way station in response to the first impulse of the stepping cycle. Obviously, it would be desirable to have some of the wayside locations unresponsive to certain cycles, whereas other wayside loca tions would respond to such cycles, so that a more economical system would result in that none of the wayside locations would require apparatus which would respond to each step in each cycle.

Putting it in other words, it is proposed in accordance with the present invention to employ a synchronous selector system in which means is provided for distinctively starting the way station selectors, depending upon whether the first stepping impulse is of positive polarity or is of negative polarity. Generally speaking, the system, in accordance with the present invention is preferably divided in two parts, the selectors of one part of which start only if the first impulse in the stepping cycle is one of positive polarity, and the selectors of the other part of which start only if the first impulse is one of negative polarity, whereby the total impulses of a particular cycle can be approximately half the total number of message circuits of the entire system.

Another feature of the present invention consists in the provision of means for normally holding the system at rest, and consists in means for initiating a cycle of stepping impulses in which the first impulse is of positive polarity in the event that a lever is operated which requires a cycle of operation the first impulse of which is of positive polarity to transmit the desired control, and in providing means for initiating the system with a starting impulse of negative polarity in response to a lever movement, providing the lever moved is one of which transmits its control only during a cycle of impulses the first of which is of negative polarity; and in the provision of means for operating the system through both of these cycles in the event there is a way station which is in condition for transmission of a change in traffic conditions, such as track occupancy.

Other objects, purposes and characteristic features of the present invention will in part be 5 understood from the accompanying drawings and will in part be pointed out in the description hereinafter.

In describing the invention in detail, reference will be made to the accompanying drawings in 10 which:-

Figs. 1A and 13, if laid end to end constitute a conventional showing of the devices and circuits in the central operators olfice of the centralized traffic controlling system; and, 15

Fig. 2 conventionally shows two way stations of one form of way station apparatus adapted to be controlled by, and transmit indications to, the central office equipment shown in Figs. 1A and 1B.

The present invention contemplates operating 0 the switch machines and signals at a large number of passing sidings on single track railroads, on double track railroads, at small interlocking plants, and in fact at any location where train movement must be dictated from a central office, such for instance as the junction point of a branch road with the main line. In other words, in accordance with the present invention there will be many wayside locations, even though the particular portion of the invention illustrated in the 0- drawings shows only two such Wayside locations, one at the west end of a passing siding PS and the other at the east end of such passing siding. It

is contemplated that in the central ofiice the entire railway system, to which the present inven- 35 tion is applied, is reproduced in miniature, as con ventionally shown by the miniature passing siding ps (see Fig. 1A).

The passing siding PS (see Fig. 2) has the two track switches associated therewith, controlled by 4 switch machines SM and SW. The east end track switch is provided with the usual detector track circuit insulated from the rest of the system by insulating joints l6, and includes the usual track battery I! and the usual detector track relay 45 TR the west end of the passing sidings includes a similar track circuit, including a track battery l8 and a track relay TR The east end of the passing siding PS is provided with the usual main starting signal EM, dwarf starting signal E main 50 entering signal WM and dwarf entering, or takesiding, signal W These switch machines SM and SM and the signals associated with the track switches controlled by these switch machines, are controlled over the selector system embodying the 55 present invention, and of which only one specific embodiment has for convenience been illustrated.

Referring to Fig. 2 it will be noted that the series of stepping relays I 2 3 4 and 5 are controlled by the line relay U3 and the slow acting relay I whereas the stepping relays H I2 I 3 M and I5 are controlled by the line relay LR and the slow acting relay 1 It is contemplated that the polar magnetic stick type relays SR and DB which are used for controlling the signals at the west end of the passing siding PS, and the switch machine polar magnetic stick type relay SMR which controls the switch machine 5M will be controlled over the message line 20 through the medium of the stepping relays of that wayside location, namely, way station No. 1. Similarly the corresponding relays SR DR. and SMR are controlled over the same message wire 20 through the medium of the stepping relays at the local ofiice at the east end of the passing siding PS, namely, way station No. 2.

Attention is directed tothe fact that the wiring of the various relays associated with way station No. 1 is exactly the same as the Wiring of the various relays of way station No. 2, except in one particular, namely, that the main control contact ill of the line relay LR has its left hand stationary contact 25 connected to the positive terminal of the battery iii and has its right hand stationary contact 25 connected to the negative ter-y I minal of this battery 3!, whereas the stationary contacts of the corresponding movable contact 23 of the line relay LE has its stationary contacts connected to the opposite terminals of the corresponding battery 32.

'picked up after a short time. Also, attention is directed, to thefact that with the line relays LE and LR operated toward the right, the stepping relay t will be picked up and the stepping relay l i will not be picked up, this because both sides of the coil of the stepping relay l I are connected to the same side, namely the positive terminal, of the battery 32. If, on the other hand, the line relays LE and LR are operated toward the left during the first step, and before the slow acting relays I and I have picked up, the stepping relay' l E will pick up and the stepping, relay I will not'pick up. In other words, the stepping relays of way station No. 1 areoperated only in the event that the operating cycle is started with a positive polarity impulse, and the stepping relays of way station No. 2 will only be operated in the event that the operating cycle is started with a. negative impulse.

Let us now refer to Figs. 1A and 1B and observe the central oifice apparatus required to create the two diiierent kinds of cycles of impulses, and the manner in whichthis ofiice equipment cooperates with the wayside apparatus. The relays LR W CR E E E I A B I 2, 3, t and 5 shown in Fig. 1A correspond respectively to the relays LR W CR, F F F 1', A B, H, [2, l3, i l and shown in Fig. 1B. These two groups of relays may be said to be the relays which enter into the stepping organization of the central oiliceequipment. I

The transfer relay TB, is a relay that selects whether the stepping apparatus shown in Fig. 1A or the stepping apparatus shown in Fig.13 shall be operated, and in thisconnection it may be stated, that the stepping apparatus shown in Fig. 1A applies a starting impulse of positive polarity, whereas the stepping apparatus shown in Fig. 1B starts its cycle of impulses by an impulse of negative polarity. It may also be stated here, that the relay FA (see Fig. 1A) is a field starting relay, and is provided to initiate first the apparatus shown in Fig. 1A and then the apparatus shown in Fig. 1B, or vice versa, in the event a change of indication is to be transmitted from a wayside local oflice.

Also, it may be pointed out that the lever LS controls the signals at the west end of the passing siding PS, the lever LISM controls the switch machine SM the lever LS controls the signals EM, E WM and W and the lever LSM controls the switch machine SM Similarly, the indicating relays IR. and IR are controlled through the medium of the selector system in accordance with the condition of occupancy of the detector track circuits including track relays TR and TR, respectively.

The relays A B A and B may for convenience be called repeat-cycle relays, in that they cause the apparatus to go through two successive cycles in response to each initiation of the portion of the system in which they are contained.

The relays E E E F F and F may conveniently be called master relays, in that these relays are the ones that supply stepping current to the stepping Wire 36. Three of these relays are used, even though one would sufiice, three being used in order to slow down the stepping operation of the system, and in this case it should be noted that the relay E repeats the relay E and the relay E repeats the relay E, as is also true of the relays F F and F The relays W and W may conveniently be called control relays, because they must be energized in order to connect the stepping line to the central office equipment, or in other words they determine whether stepping impulses shall be transmitted to the way station apparatus.

The relays CR and CR) may conveniently be called starting relays, in that these relays again pick up respectively the relays W and W after the completion of a cycle of operation followed by the necessary period of blank, which period of blank is determined by the time required for the slow acting relays I and l to again assume their deenergized position.

The relays LR? and LR are of course the line relays, and the relays l, 2, 3, t, 5 and H, l2, l3, I l and I5 are the stepping relays, or channel completing relays, a separate message channel extending from the central cfiice equipment to a channel relay or channel contact at a distant way station, such a message channel being completed for each step in a cycle of operation of the system.

Having now briefly pointed out the purpose for which each relay of the system is used, it is considered expedient to consider the operation of the system in order to get a more clear understanding of the operating characteristics of the system and the economy experienced in dividing the various way stations into two groups, one group of which is operated only in the event a cycle is started with an impulse of positive polarity and the other group of which is only operated in the event the cycle is started with, an,

impulse of negative polarity, each of these groups including a large number of way stations.

Operation-Let us assume that the selector system is in its normal at-rest condition and that the central oliice operator anticipates the.

approach of an east bound train which is to take the side track of the passing siding PS, and that he wishes to operate the switch machine SM to the take-siding position. The operator will first move the switch machine lever LSM from its right hand normal position to its left hand dotted position, thereby momentarily closing a pick-up circuit for the relays A and B readily traced in the drawings and including the wires 33 and 34. With this circuit momentarily completed the relays A and B will pick up, and the relay A will have its stick circuit, including its stick contact 35 and the back contacts 30 and 3l of the relays I and CR in multiple closed,

so that the relay A will remain energized by current flowing in this stick circuit after the momentary closure of the pick-up circuit no longer maintains this relay energized. Similarly, a stick circuit is closed for the relay B which includes its stick contact 38 and the back contact 39 of the channel selecting relay 4. In this connection it should be noted that the stick circuit for the relay l2 also includes the upper winding of the relay A so that the relay A will not drop even though its stick circuit including its stick contact is temporarily opened.

With the relay A picked up and its contacts 30 35, M, 42 and 43 closed, the closure of the contact 43 completes an energizing circuit for the transfer relay TR. This circuit may be traced as follows:--beginning at the terminal B of a suitable source of direct current, back contact 44 of the relay A (see Fig. 1B) wire 45, front contact 43 of the relay A wires 46 and ll, upper winding of the transfer relay TR, to the other terminal B of said source of current.

The completion of this circuit operates the transfer relay TR toward the left, thereby breaking the line circuit 30 insofar as the apparatus of Fig. 1B is concerned at the contact 48 of the relay TR, this contact 48 in its left hand position connecting the stepping wire 30 to the branch stepping line 30* connected to the apparatus shown in Fig. 1A. Also, operation of the contact 49 of the transfer relay TR to its left hand position completes the following circuit for the starting relay CRPz-beginning at the terminal 3-, contact 49 of the transfer relay TB in its left hand position, wire 50, front contact II of the relay A Wire5I, winding of the starting relay CR, wire 52, back contact 53 of the relay I to the other terminal 3-]- of said source. The com- 55 pletion of the circuit just traced picks up the starting relay CR", which relay CR then closes a pickup circuit for the control relay W including the front contact 31 of the relay CR and readily traced in the drawings. With the relay W assuming its energized position the stepping line 30 30 is closed at the front contact 55 of the relay W but this stepping circuit is still open at the contacts 54 and 85 of master relays E and E Also, picking up of the relay W applies current to the upper winding of the master relay E operating this relay E to a right hand position, which circuit may be traced as follows:starting at the terminal B+, front contact 56 of the relay W wire 51, back contact 58 of the stepping relay I, wire 59, back contact 60 of the stepping relay 2, wire BI, back contact 52 of the stepping relay 3, wires 83, 64 and 65, upper winding of the relay E to the terminal B. The completion of this circuit causes the relay E to be operated toward the right, thereby causing its contacts 68 to apply current to the upper winding of the relay E which current then operates the relay E? to the right and causes its contact 61 to apply current to the upper winding of the relay E thereby operating this relay to the right. With the relays E E and E assuming the right hand position, the step ping line 30 is energized by current of positive polarity through a circuit which may be traced as follows: beginning at the terminal B+ of the central office battery, contact 54 of the relay E toward the right, wire 86, contact 85 of the relays E to the right, wire 68, front contact 55 of the relay W wire 69, line relay LR, wire 38*, contact 58 of the transfer relay TR. (see Fig. 1B) wire 30, line relay LR, (see Fig. 2), line wire 30, line relay LR line wire 30 connected to the common return wire C at the distant end of the system, which common return wire C, may be grounded if desired, and is connected to the mid-point of the central oifice battery or other suitable direct current source.

The flow of current in the circuit just traced causes all of the line relays LR, LE LE2, etc. to be operated toward the right. Movement of the contact I0 of the line relay LR toward the right completes an energizing circuit for the stepping relay I as followsz-beginning at the terminal 13+, contact I0 of the relay L15. to the right, wire I I, back contact I2 of relay I wire I3, bottom winding of the stepping relay I, wires M and 'l5, back contact I8 of the stepping relay 2, wires TI and I8, to the other terminal B-. The completion of this circuit picks up relay I, which then sticks up as soon as the relay I reaches its energized position. This stick circuit may be traced as follows:beginning, at the terminal B+, front contact 53 of the relay I wires and BI, stick contact 82 of the relay I, wire 83, upper winding of the relay I, wires 84 and '85, back contact 15 of the relay 2, wires TI and '58 to the other terminal B.

Similarly, movement of contact 2| of the relay LR toward the right, closes the following pick-up circuit for relay Pt-beginning at the negative terminal of the battery 3!, wires 2'? and 28, contact ?.I of relay LE wire I02, back contact I03 of the relay I wire I04, lower winding of relay I wires I05 and I05, back contact I01 of the relay 2 wires I08 and I09, to the positive terminal of the'battery. The relay I when once picked up will of course stick up through the following stick circuit after relay 1 has picked up:--beginning at the negative terminal of the battery 3|, wires H2 and H3, front contact II4 of relay I wires H5 and H6, stick contact Ill, wire IE8, resistance H9, upper coil of relay 5 wires I20 and I08, back contact I01 of relay 2 wires I08 and I09, back tothe battery 3!.

With the relay I picked the main circuit for the upper winding of the relay E is broken at the back contact 58 of the relay I, and an auxiliary energizing circuit for the upper winding of the master relay E is completed which auxiliary energizing circuit may be traced as follows:beginning at the terminal B+, front contact 55 of the relay W wire 51, front contact 59 of the stepping relay I, wire 81, front contact 88 of the relay CR wires 89 and 55, upper winding of the relay E to the other terminal B.

Picking up of the slow acting relay I breaks the energizing circuit for the starting relay CR at the back contact 53 0f the relay I thus dropping the control relay CR 'and causing its contact 88 to shift the circuit forenergizing the relay E from the upper winding to the lower winding of the master relay E and this shifting of the auxiliary circuit from the upper to the lower winding, these windings having their turns oppositely arranged, causes the master'relay E to be operated toward the left. Also, picking up of the slow acting relay I completes the following stick circuit for the relay W n-beginning at the terminal B+, front contact 36 of the relay I wire 90, back contact 9| of the stepping relay 5, wire 92, front st-ickcontact 93 of the relay W wires 94-and 95, winding of the relay W to the other terminal B, so that this relay W is stuck up and remains stuck up until either energization of the relay 5 has taken place or deenergization of the relay I has taken place.

The application of stepping current of positive and then of negative polarity alternately to the stepping wire 30 will of course operate the line relays -LR, and LR It has been heretofore pointed out that dropping of the relay CR has shifted the circuit from the upper to the lower coil of the mas'ter'relayE and has caused this relay E to be operated to the left. This in turn causes the relays E and E to be operated toward the left, therebycompleting the following circuit for energizing the stepping line 39 with negative polarityt-beginning' at the terminal B, contact 98 of the relay E wire 99, contact 85 of the relay E toward the left, wire 68, front contact '55 of {the relay W Wire 69, line relay LR wire 39, contact 48 of the transfer relay TR, to the steppingwire 3'0 and through relays LR and LR to the distant end, which is connected to the common return wire C, which common return wire C is in turn connected to the mid-point of a suitable three' terminal battery or generator (conventionally represented by the reference characters 3+, 3- and C) in the central office. Operation'of the line relay LR toward the left will close the pick-up circuit for the bottom winding of the stepping relay 2 through a circuit readily traced in the drawings and including a front .conta'ct I09 of the relay I and back contact I23 of the relay 3.

Similarly at way station No. 1, operation of the linerelay LR (see-Fig. 2) to the left, picks up the relay 2 through a circuit readily traced and including front contact I24 of the relay I "and back contact I25 of the relay 3 Picking up of the relays 2 and 2 will of course drop the relays I and I by reason of lifting of the contacts I6 and H11, respectively. Dropping of the contact 58 of the relay I (see Fig. IA), removes energy from the wire 81, so that neither of the two auxiliary circuits for the relay E can hereafter be completed; also, dropping of this contact58 applies current to the upper winding of the relay E through the followingcircuitz-beginning at the terminal 13+, front contact 56 of the relay'W wire 51, back contact Bil-of the relay I, wire 59, front contact 60 of the relay 2,.wires I9, 64 and 65, upper winding of the relay E to the terminal B. The flow of current in this circuit will operatethe' relay E to the'right; which for reasons heretofore given-causes the relays E and E to be sequentially moved to the right, thereby again ap' plying stepping. current ofpositive polarity to" the stepping circuit 39, and affecting operation of-the relays LR), LE and LE to'the right.

With these linerelays'operated to the'right hand position the stepping relay 3 is picked up through a circuit readily traced in the drawings-andincludinga front-contact I33 of the relay 2 and the back contact I34 of 'the relay 4, and similarly the relay 3 (see Fig. 2) is picked up through the medium of the front contact I35 of the relay'2 and the back contact I39 of the relay 4 These relays 3 and 3 having once been picked up will be stuck up through circuits readily traced in the drawings.

Attention is directed to the fact that when the slow acting relays I and I were picked up the lifting of the contacts I3EI'and I3I of these relays disconnected the message wire 20 from the starting circuit branches, which will be described hereinafter, to the message branches of the two stepping relay groups I-5, and I -5 It will be remembered that the operator moved the lever LSM toward the left and thereby initiated operation of the system by picking up the relays A and B through the medium of wires 33 and 34. With the relays 3 and 3 now picked up and stuck up, even though these relays only remain in their energized stuck-up position for a moment, the following message circuit is completed for a sufficient period of time to operate the switch machine relay SMR to its left hand positionz-beginning at the terminal B, contact I38 of the lever LSM wire I39, front contact I46 of the stepping relay 3, wire I iI, back contact I42 of the relay 2, wire I93, back contact I44 of the relay I, wire I45, contact I45 of relay E to the right, wire I47, contact M8 of the relay E to the left, (this message circuit being completed when the relays E and E have already been moved to the left but the relay E has not yet been moved to the left during the fourth step of these relays), wire I99, front contact I39 of the relay 1 message wire 29, wire I59, (see Fig; 2) front contact I3I of the relay I wire I5I, back contact I52 of the relay I wire I53, back contact I54 of the relay 2 wire I55, front contact I56 of the relay 3 wire I57, winding of the switch'machine relay SMR wire I58, front contact I59 of the relay 3 wire I59, back contact I6I of the relay 4 wire I62, back contact I63 of the relay 5 wire I64 of the common return wire C connected to the mid-point of the central oflice battery.

The flow of current of negative polarity through this relay SMR operates this relay to its left hand dotted position, and since this relay SMR is of the magnetic stick type, it will remain in the left hand position after having been operated there in response to the momentary flow of current of negative polarity. Attention is directed to the fact that the message circuit at way station No. 1, just traced, includes back contacts of the relays I 2 4 and 5 and includes front contacts of the relay 3 The purpose of this feature is to check the positions of the'various relays, so that the unauthorized sticking up of a channel or stepping relay will prevent the closure of any message circuit. In this connection it should be noted that the stepping relay 5 is not used as a channel selecting relay, it having no channel through a front contact, but is merely used to check against a false sticking up of the relay 4 In other words, if one of the relays should remain up, for any reason, the picking up of a second relay would not permit any message channel circuit to be completed. Putting it another way, the channel circuit branches are so'interlocked that no channel circuit can be completed when two of these relays are in their energized positions.

After a short interval of time the relay E will also be operated to the left hand position in response to movement of the relays E and E toward the left, the relay E having been moved toward the left in response to the application of current of positive polarity to the wire E66. Operation of the relay E to the left applies current of negative polarity to the step- I ping wire 3%, thereby operating the relay LR and LE toward the left and closing pick-up circuits for the relays t and 8 which include the front contact iii? of relay 3 and back contact I68 of relay 5, and the front contact I69 of relay 3 and back contact N9 of relay respectively. These relays 4 and 4 will then be stuck up through stick circuits readily traced in the drawings, and will effect deenergization of the relays 3 and 3 Dropping of the relay 3 will again apply current of positive polarity to the wire 64 leading to the upper coil of the relay E thereby operating the relay E toward the right, and this relay E in turn will effect operation of the relays E and E toward the right. Movement of the relay ll toward the right causes current of positive polarity to be applied to the stepping wire 99, thus operating the line relays LR and LR toward the right, and thereby picking up the relays 5 and 5 through pick-up circuits including the front contact I12 of relay 4 and I13 of relay 4 respectively. The relays 5 and 5 will then be stuck up through stick circuits readily traced in the drawings, and for obvious reasons their picking up will efiect deenergization of the relays 4 and 4 Picking up of the relay 6 heretofore opened the stick circuit including" the relay B and the upper coil of the relay A thereby effecting deenergization of the relay B but the relay A remained stuck up through its stick circuit including its contact and the back contact 31 of the relay w CR Also, picking up of the relay 5 as has just happened, will open its back contact 9! and thereby break the stick circuit for the relay W to effect deenergization of this relay W With the relay W deenergized the line circuit :1 39 is deenergized, thereby causing the line relays LR LE and LE to assume their deenergized pendent positions, and with the contacts 28 and 22 of the relays L15, and LE assuming their pendent position the relays I and I will assume 50 their deenergized positions. Dropping of the relay I will effect dropping of the relay 5 by reason of opening of contact Il l of relay I Dropping of the relay l1 will, through the medium of its front contact 53 drop the relay 5, and through the medium of its back contact 53 again picks up the starting relay CR the contact M of the relay A still being closed, and the transfer relay TR still assuming its left hand dotted position. U0 Picking up of the relay CR again closes the pickup circuit for the relay W through its contact 31, and this relay W will then again apply current of positive polarity to the stepping line 39, thereby causing the relays I and I again to be picked up in response to movement of line relays LR and LR toward the right, and also effecting picking up of the slow acting relays I and I Picking up of the relay I will of course again close the stick circuit for the relay W at the front contact 3% of the relay I The entire cycles of operation of the portion of the system shown in Fig. 1A and the way station No. 1 will then be repeated. In this connection it should be noted that during the time when the relay I has already been picked up and the relay CR QLI has not yet dropped in response to this picking up of the relay I the stick circuit for the relay A is open at the two back multiple contacts 36 and 31 of the relays I and CR, so that the relay A assumes its deenergized position and the system comes to a stop at the end of a second cycle, this because the starting relay CR has its energizing circuit broken at the contact GI of the relay A at the time of dropping ofrelay I at the end of the second cycle, so that the relay CR remains down until the relay A is again picked It has been pointed out how the switch machine relay SMR is moved to the left hand dotted position, this movement of the relay SMR to the left effects operation of the switch machine SM to its take-siding position through suitable means conventionally shown by the dotted line I15, so that the east bound train may pass into the side track of the passing siding PS.

Let us now assume that the central office operator, after having allowed another train to move over the main track, wishes to allow the east bound train to continue its east bound movement, and therefore moves the switch machine lever LSM to its left hand dotted position. This movement of the lever LSM to its left hand position momentarily applies current to the repeat cycle relays A and B through-the following circuit:-

starting at the terminal 13+, lever LSM wires I11, I18, I19, and I89, winding of the relay B wire I8I, upper winding of the relay A to the terminal B-. With the relays A and B picked up, the relay A will be stuck up through its stick contact I82, and the back contacts I83 of relay I and 584 of relay CR in multiple, and the relay B will be stuck up through its stick contact I85 and the back'contact I85 of the stepping relay I4.

With the relays A and B energized and the relay A deenergized, the lower winding of the transfer relay is energized through the following circuit-beginning at the terminal B+, back contact 42 of the relay A wire I99, front contact I9I of the relay A wires I92 and I93, lower winding of the relay TR, to the terminal B The completion of this circuit operates the transfer relay TR back to its normal position, thereby connecting the stepping wire 38 to the stepping line 30. Movement of the transfer relay TR to its right hand position also closes the following circuit for the starting relay CR :-beginning at the terminal B-, contact 49 of the transfer relay TR, wire I95, front contact 96 of the relay A wire I91, winding of the starting relay CR,

wire E98, back contact I99 of the relay I back to terminal B+ of the same source. Picking up of the starting relay CR closes the pick-up circuit for the control relay W through a circuit including the front contact I84 of relay CR and the wires 290 and 2!.

Picking up of the relay W applies current to the lower winding of the master relay F through the following circuit:-beginning at the terminal B+, front contact 203 of the relay W wire 294, back contact 295 of the relay Ii, wire 29%, back contact 201 of the relay I2, wire 298, back contact 209 of the relay I3, wires 2H3, Eli, and 2I2, lower winding of relay F The application of current to the lower winding F movesthis relay F to its left hand position thereby sequentially operating the relays F and F to their left hand dotted position, and movement of the relay F to its left hand position applies current of negative polarity to the stepping wire 39 through the fol- 10 nected to the mid-point of the central office battery. It is of course noted that during this energization of the stepping line 36, the line relay LR is not included in the circuit whereas heretofore the line relay LR, was not included in this circuit, so that the line relays LR", LR LR,

will now be simultaneously operated to their left hand position.

Operation of the line relay LE to its left hand position closes the following pick-up circuit for the relay ll :beginning atthe negative terminal of the battery 32, wires 220, 22! and 222, contact 23 of the relay LR, to the left, wire 223, back contact 224 of the relay I wire 225, lower winding of the relay H wires 226 and 227, back 25 contact 228 of the relay I2 wires 229 and 230, back to the battery 32. The completion of the circuit just traced picks up the relay H which then in response to picking up of the relay I is stuck up through the following stick circuit:

beginning at the negative terminal of the battery 32, wires 220 and 232, from contact 233 of the relay I wires 234 and 235, front stick con- 4 tact 236 of the relay H resistance unit 231, up- "per winding of the relay H wires 238 and 221,

back contact 228 of the relay I2 wires 229 and 236, back to the battery 32.

It may be pointed out here, that the resistance unit 231, which is included in a stick circuit just traced, is used for the purpose of decreasing the quently reduces the arcing at the contacts when the relay I is again deenergized by breaking of this stick circuit. It is of course understood that after a relay is once picked up it will stick up on a much smaller current than is required to pick such relay up.

Referring now to way station No. 1 it will be noted that movement of the line relay LR. toward the left will after a short time effect energization of the slow acting relay I but will not effect energization of the stepping relay l because the circuit closed through the lower winding of the relay I does not include a source of energy, both terminals of this lower winding of relay 1 terminating at the positive side of the battery 3|.

M been described in connection with the apparatus in Fig. 1A, it is deemed unnecessary to specifically describe all the steps of this operation and to trace all the various circuits involved. It may be pointed out that the principal difference between the stepping apparatus shown in Fig. 1A and the stepping apparatus shown in Fig. 1B is that initiation of the system shown in Fig. 1A causes the relays E E and E to be moved to the right in response to energizationof the upper coil of 7 relay E whereas the initiation of the system shown in Fig. 1B causes the relays F F and F to be moved to the left in response to energi'z'ation of the lower winding of relay F in all other respects relays in Fig. 1A are wired exactly the 75 same as are the corresponding relays in Fig. 13,

Similarly, referring to Fig. 2, the relays LR I 1 2 3 4 and 5 are wired up exactly the same as are the relays LE I H I2 I3 I4 and I5 respectively, except that the contact 2| of relay LR when in its right hand position is connected;

to the negative terminal of the battery 3!, whereas the corresponding contact 23 of the line relay LE when assuming its right hand position is connected to the positive terminal of the battery 32, from which it is apparent that the bank. of stepping relays shown at way station No. 1 will only operate if the first impulse of the cycle is of positive polarity, whereas the stepping relays at the way station No. 2'will only operate if the first step of the cycle of impulses is of negative polarity.

From the foregoing it is apparent that the stepping relay I3 and the stepping relay l3 will assume their attracted positions simultaneously and during the time when these two stepping relays I3 and I 3 are up and their adjacent stepping relays are down, and while the relay F assumes its right hand position and the relay F assumes its left hand position the following message circuit, for operating the switch machine for SMRP, is closedz-beginning at the terminal B, contact 246 of the lever LSM assuming its left hand position, wire 24!, front contact 242 of the relay l3, wire 243, back contact 244 of the relay 12, wire 245, back contact 246 of the relay wire 241, contact 248 of the relay 1: toward the left, wire 249, contact 256 of the relay F to the right, wire 25I, front contact 252 of the relay I wire 253, message wire 20, wire 254 (see Fig. 2), front contact 255 of the relay I wire 256, back contact 251 of the relay H wire 258, back contact 259 of the relay I2 wire 266, front contact 26! of the relay I3 wire 262, winding of the switch machine relay SMR wire 263, front contact 264 of the relay I3 wire 265, back contact 266 of the relay I 4 wire 261, back contact 268 of the relay 5 wire 269, to common return wire C connected to the mid-point of the central office battery.

Completion of the circuit just traced operates the switch machine relay SMR to its left hand dotted position, thereby operating the switch machine 8M to its take-siding position, allowing the east bound train to move ofi of the siding as soon as the dwarf signal E is cleared.

This dwarf signal E may be cleared by operation of the signal relay SR to its right hand position, the direction relay DR, already assuming its east bound position, and this relay SR may be operated to its right hand position by movement of the signal lever LS to its right hand position, whereby during the simultaneous energization of the stepping relays H and II causes a momentary flow of current to the signal relay SR through a message circuit readily traced in the drawings. This flow of current operates this relay SR to its right hand position, thereby clearing this dwarf starting signal E through a suitable circuit conventionally shown by the dotted line 270, all in a manner as clearly disclosed in the prior application of S. N. Wight,

Ser. No. 321,185, filed November 22, 1928.

As the east bound train now proceeds into the single track section in response to clearing the dwarf starting signal E it will tread upon the detector track circuit and effect deenergization of the track relay TR Dropping of the track relay TR effects momentary energization of the relay QR through the following circuit:-beginning at the terminal B+ and back contact 2' of the relay TRF, wire 212, front contact 213 of the relay PR wires 214 and 215, winding of the relay QR to the other terminal B-. It may be mentioned here that if the system is at this 5 time in operation the relay QR. will be stuck up through a stick circuit including the stick contact 276 and the front contact 21'! of the relay 1 Also, upon picking up of its detector track relay TR or any other relay the position of which is to be indicated in the central ofiice, the relay QR. will be picked up through the back contact 273 of the relay PR the relay PR being slower acting than the relay QR For a more complete description of the relays PR and QR attention is directed to the prior application of R. C. Leake and R. M. Phinney, above referred to.

Picking up of the relay QR. closes the following circuit for the field starting relay FA:be-

ginning at the positive terminal of the battery 230 (see Fig. 1A), winding of the field starting relay FA, wire 28I, back contact I30 of the relay I message wire 20, wire 254 (see Fig. 2), back contact 255 of the relay I wire 282, front contact 283 of relay QR to the common return wire C connected to the negative terminal of the battery 285 Momentary energization of the relay FA, causes it to close its contacts 284 and 285, thereby closing pick-up circuits for the relays A B A and B readily traced in the drawings.

With these four relays simultaneously energized the transfer relay TR will be left in the position it is then assuming, and if it is then assuming I the left hand position it will initiate the apparatus shown in Fig. 1A, whereas if it assumes its right hand position it will initiate the apparatus shown in Fig. 1B, and in each case after the apparatus first selected has been operated through one cycle, all in a manner as heretofore described, the A relay of that apparatus will drop at the end of the second cycle. Before the A re lay drops, and specifically when the last stepping relay of that group picks up, the transfer relay TR will be operated to its opposite position.

Let us now consider more specifically this operation of the transfer relay TR. Let us take up the operation where we left it, that is, with the relays A B, A and B all energized and with the first cycle completed. Just before this cycle was completed, namely with the the stepping relay 5 up, completionof the following circuit operates the transferrelay TR to its right hand position:beginning at the terminal 13+, front contact 44 of the relay A wire I27, front contact I25 of the stepping relay 5, wires I28 and I 93, bottom coil of the relay TR, to the other terminal 18-. With the relay TR assuming its right hand position and the relay A assuming its attracted position, the apparatus shown in Fig. 1B is operated through one cycle of operation in a manner as already described. When, during this cycle of operation of the apparatus shown in Fig. 1B, the relay I5 assumes its energized position, the transfer relay TR is oper- 5 ated to its left hand position through the following circuit:-beginning at the terminal B+,

front contact 42 of relay A*, wire I3'l, front contact I38 of the stepping relay I5, wires I39 and 4?. With the transfer relay now assuming its 7 left hand position and the relay A still up, the apparatus shown in Fig. 1A is again operated through a cycle of operation, at the end of which the relay A is deenergized. With the relay A now deenergized and relay A still energized the transfer relay TR is again operated to its right hand position in a manner presently described in detail.

Briefly stated, this transfer relay TR can only be operated in a manner presently described if one of the relays A or A is energized and the other is deenergized, from which it is apparent that if both of these relays A" and A are simultaneously energized the transfer relay TR can only be operated through the medium of contacts I26 and I38 of relays 5 and I5, respectively, so that the transfer relay will, with both of the relays A and A energized select that half of the dispatchers equipment previously selected by the transfer relay TR depending upon the position it then assumed, and that as soon as a cycle is completed or one of the relays A or A is deenergized the transfer relay TR will be operated to the opposite position.

I have now pointed out how the system may be initiated from the field and how such initiation from the field causes the apparatus in Fig. 1A to operate through one cycle of operation, the apparatus shown in Fig. 13 to operate through one cycle of operation, after which the apparatus of Hg. 1A again operates through one cycle followed by a cycle of operation of the apparatus shown in Fig. 1B, from which it is apparent that during such operation, the relays I4 and I4 will be simultaneously assuming their attracted positions andwhen this occurs the indicating relay IR. (see Fig. 1A) is operated by current of negative polarity through the following message circuit: beginning at the negative terminal of the battery 290 (see Fig. 2), back contact 29I of the relay TR wire 292, front contact 293 of the relay I4 wire 294, back contact 25I of the relay I3 wire 260, back contact 259 of the relay I2 wire 258, back contact 251 of the relay H wire 256, front contact 255 of the slow acting relay I wire 254, message wire 20, wire 253, front contact 252 of the relay 1', wire 25I contact 250 of the relay F to the right, wire 249, contact 248 of the relay F to the left, wire 241, back contact 246 of the relay II, wire 245, back contact 244 of the relay I2, wire 243, back contact 242 of the relay I3, wire 296, front contact 29? of the relay I4, wire 29B, winding of the relay 1R to thecommon return wire C connected through wires 269 (see Fig. 2), back contact 268 of relay I5 wire 251, front contact 255 of relay I4 and wire 299 to the mid-point of the battery 29!]. The completion of this message circuit will of course operate the indicating relay IE to the left and illuminate the lamp L manifesting to the operator that the train is leaving the passing siding at the east end. The relays QR and PR are provided for the same purpose and function in the same way as do the relays QR and PR Summary operation-Considering the system at rest and with the relays all positioned as shown, and assuming that the system is initiated by moving either the lever LS or the lever LSM the following relay operations will take place:- relays B and A pick up, stick circuits for relays B and A completed, top coil for transfer relay TR energized operating TR to left, relay CR, energized, relay W energized, top coils of relays E E and E energized operating these relays to the right, line relays LR and LR operated to the right, relays I and I picked up and stuck I up and message circuit completed, top coil relay E opened and auxiliary circuit for top coil of relay E closed, relays I and I picked up, stick circuit for relay "W completed, relay CR. dropped,

' bottom circuit for relay E closed and auxiliary circuit for top coil of relay E1 opened, operates relays E E E to the left, line relays LR and .of relay E closed, line relays LR and LE operateol to the right, relays 3 and 3 picked up, relays 2 and 2 dropped and third message circuit completed, main circuit for upper coil of relays El opened and main circuit for lower coil "of relay E closed, relays E E and E operate to left, line relays LR and LR operate to left, relays t and d picked up, relay B dropped, relays 3 and 3 dropped and fourth message circuit completed, main circuit for bottom coil relay E opened and main circuit for top coil of relay E closed, relays E E E LR and LR, operate to right, relays 5 and 5 picked up, relays t and d dropped and fifth message circuit completed, relay W dropped opening the stepping circuit, relays LR and LE deenergized, relays I and I dropped, relay CR. picked up, relay W picked up, after which the same cycle of operation is repeated. It may be pointed out here that the devices are not necessarily operated in t the exact order above given in that some of these operations occur in multiple, so to speak, so that the exact order in which these operations take place depends somewhat on the operating characteristics of the relays involved. This summary of relay operations has for convenience been limited to the positive starting portion of the system, and has been given to aid a person in the study of the system disclosed in the drawings.

Although applicant has illustrated one rather specific embodiment of his invention, this is not to be construed as a limitation upon the scope of his invention, nor is the system shown to be construed as the exact construction preferably employed in practicing the invention, but should be considered as an exemplification of a system having certain desirable operating characteristics underlying the present invention; for instance, suitable interlocking neutral relays could be used instead of the polar relays E E and E and other suitable control relays may be used instead of the relays. SR DR SMR etc., and many other changes, modifications and additions may be made to adapt the invention to the particular problem encountered in practicing the same,

without departing from the spirit or scope of the invention, except as demanded by the scope of the following claims.

What I claim as new is: I 1. In aremote control system of the synchronous selector type, the combination with two separate series of stepping relays in a central oifice and a series of stepping relays at each of a plurality of way stations, means whereby one of said two series of stepping relays operates to apply a series of stepping impulses to a stepping line connecting said ofiice and way stations the first H of which is positive, means whereby the other of "said two series of step-ping relays operates to aping stepping relays assume their energized position.

2. In a remote control system of the synchronous selector type, the combination with two separate series of stepping relays in a central office and a series of stepping relays at each of a plurality of way stations, means whereby one of said two series of stepping relays operates to apply a series of stepping impulses to a stepping line the first impulse of which is positive, means whereby the other of said two series of stepping relays operates to apply a series of stepping impulses to said stepping line the first of which is of negative polarity, means whereby some of said way station series of stepping relays respond only when the first impulse of a series of impulses is positive, means whereby other series of way station relays respond only when the first impulse of a series is of negative polarity, and means completing a plurality of message circuits sequentially each including the same line wire during a particular cycle of operation.

3. In a remote control system of the synchronous selector type, the combination with two separate series of stepping relays in a central ofiice and a series of stepping relays at each of a plurality of way stations, means whereby one of said two series of stepping relays operates to apply a series of stepping impulses to a stepping line the first of which is positive, means whereby the other of said two series of stepping relays operates to apply a series of stepping impulses to said stepping line the first of which is of negative polarity, means whereby some of said way station series of stepping relays respond only when the first impulse is positive, means whereby other series of way station relays respond only when the first impulse of a series is of negative polarity, and means completing a plurality of message circuits sequentially each including the same line wire during each of the two distinctive cycles of operation obtainable by said two separate series of stepping relays.

4. In combination, a line circuit having two polar line relays therein, a series of stepping relays controlled by each of said line relays, a slow acting relay associated with each of said line relays each assuming its energized position if the associated line relay assumes either of its polar positions either intermittently or permanently, a first stepping relay of one of said series of stepping relays having an energizing circuit including a back contact of said associated slow acting relay and a contact closed if said associated line relay assumes its positive position, a first stepping relay of the other series of stepping relays having an energizing circuit including a back contact of said associated slow acting relay and a contact closed when its associated line relay assumes its negative position, whereby the first relay of one series of stepping relays is picked up only if the first impulse of a cycle is of positive polarity and the first relay of the other series is picked up only if the first impulse of a cycle is of negative polarity, and means responsive to the operation of each of said first stepping relays for selecting the next stepping relay of its series.

5. In combination, a line circuit having two polar line relays therein, a series of stepping relays associated with each of said line relays, a slow acting relay associated with each of said line relays each assuming its energized position if the associated line relay assumes either of its polar positions either intermittently or permanently, a first stepping relay of one of said se-- ries of stepping relays having an energizing circuit including a back contact of said associated slow acting relay and a contact closed if said associated line relay assumes its positive position, a first stepping relay of the other series of stepping relays having an energizing circuit including a back contact of said associated slow acting relay and a contact closed when its associated line relay assumes its negative position whereby the first relay of one series of stepping relays is picked up only if the first impulse of a cycleis of positive polarity and the first relay of the other series is picked up only if the first impulse of a cycle is of negative polarity, and means for transmitting distinctive signals as selected by additional stepping relays of a series in accordance with whether the first relay of one series or the first relay of the other series of stepping relays is energized,

6. In combination, a line circuit having two polar line relays therein, a series of stepping relays associatedwith each of said line relays, a slow acting relay associated with each of said line relays eachassuming its energized position if theassociated line relayassumes either of its polar positions either intermittently or permanently, a first steppingrelay of one of said series ofsteppingrelays having an energizing circuit including a back contact of said associated slow acting relay and a contact closed if said associated line relay assumes its positive position, a first stepping relay of the other series of stepping relays having an energizing circuit including a back contact of said associated slow acting relay and a contact closed when its associated line relay assumes its negative position whereby the first relay of one series of stepping relays is picked up only if the first impulse of a cycle impressed on said line circuit is of positive polarity and the first relay of the other series is picked up only if the first impulse of a cycle is of negative polarity,-means for transmitting distinctive signals as selected by additional stepping relays of a series in accordance with whether thefirst relay of one series or the first relay of the other series of stepping relays is energized, and a circuit for picking up the second relay of a series including a front contact of said slow acting relay and a front contact of the first relay of the same series. a

, '7. In combination, one set of line wires, two sets of sending apparatus for transmitting distinctive signals over said one set of line wires, a two-position polar relay for eifecting use of said set of line wires by one or the other of said' sets of sending apparatus, an initiating relay for each set of sending apparatus, and meansfor operatingsaidpolar relay to one position when one of said initiating relays is energized and the other initiating relay is de-energized'and for operating said polar relay. to its opposite position when said other initiating relay is energized and said first initiating relay is deenergized.

8. In a synchronous selector centralized traffic controlling system of the message wire type comprising, a series of stepping relays, means for successively picking-up said relaysone at a time, a message wire and acommon return wire, contacts on said stepping relays for successively completing distinct message circuits one at a time and one for each stepping relay and each including said message wire and said common wire, and each of said message circuits including a contact of each of said stepping relays which contacts are so associated with said relays that in the event two relays are up at the same time no message circuit can be completed.

9. In a remote-control system of the synchronous selector type; a plurality of stations;

a stepping circuit connecting said plurality of stations; means applying a series of impulses to said stepping circuit; means determining the character of the first impulse of said series of impulses; a series of stepping relays located at each station, certain of said series of stepping relays being responsive to said series of impulses only when the first impulse is of one character, and certain other of said series of stepping relays being responsive to said series of impulses only when the first impulse is of another character; and means for transmitting distinctive signals only When certain and corresponding relays respond to said series of impulses.

10. In a remote control system of the synchronous selector type; a plurality of stations; a stepping circuit connecting said plurality of stations; means applying a series of impulses to said stepping circuit; means determining the character of the first impulse of said series of impulses; a series of stepping relays locorresponding impulses of said series of impulses.

l 11. In combination; one set of line wires; two sets of sending apparatus each being operable through cycles of operation for transmitting distinctivesignals over said one set of line wires; a two-position polar relay for efiecting use of said set of line wires during an operating cycle by one or the other of said two sets of sending apparatus; two initiating relays, one for each set of sending apparatus for starting its corresponding set of apparatus whensaid two-position polar relay is in a corresponding position and that initiating relay is energized; means for operating said polar relay to a position into correspondence with a particular initiating relay when that initiating relay is energized and the other initiating relayis deenergized; and means for operating saidpolar relay to alternate positions for "successive cycles of operation when both of said initiating relays are energized.

12. In combination, aseries of stepping relays,

means for successively energizingand successively deenergizing said relays so that only one stepping relay can remain energized at any one time, a message wire, a common return wire, and contacts on each of said stepping relays for completing a plurality of message circuits between said message wire and said common wire, each of said message circuits including a front contact of the steppingrelay energized for that step and a back contact of every other stepping relay of the series. i

13. In a remote control system, a stepping line circuit, a plurality of polarized line relays included in said line. circuit, a stepping relay bank associated with each of said line relays, means placing a plurality of series of distinctive impulses upon said line circuit, means determining the character of the first impulse of each series, and means causing only certain of said plurality of stepping relay banks to respond to any particular one of said series of distinctive impulses depending upon the character of the first impulse of such series.

'14. In a remote control system, a stepping line circuit, means placing a plurality of series of impulses on said stepping line circuit, means determining the character of the impulses of each series, a plurality of stepping relay banks, a line relay for each stepping relay bank for responding to the impulses of any series, means causing certain of said plurality of stepping relay banks to be responsive to their respective line relays only when the first impulse of a series is of one character, and means causing certain others of said plurality of stepping relay banks to be responsive to their respective line relays only when the first impulse of a series is of another character.

15. In combination, a line circuit having a plurality of polar line relays included therein, means for impressing a plurality of impulses of selected polarities on said line circuit, means responsive to said impulses for operating said line relays, a neutral relay for each polar line relay, each of said neutral relays having an energizing circuit closed when its, corresponding polar line relay assumes either of its polar positions, a stepping relay bank associated with each of said polar line relays, a pick-up circuit for the first relay in each of certain of said stepping relay banks, said circuits being energized only during the pick-up period of said-neutral relay when their corresponding polar relays assume certain polar positions, .a pick-up circuit for the first relay in each of certain other of said stepping relay banks, said circuits being energized only during the pick-up period of said neutral relays when their corresponding polar relays assume certain other polar positions, and means responsive to the operation of said polar relays following the operation of said neutral relays and said first stepping relays for operating the other stepping relays, in the associated banks.

16. In combination, .a line circuit interconnecting :a plurality of stations, a polar line relay included in said line circuit at each of said stations, means for impressing a plurality of impulses of selected polarities on said line circuit, means responsive to said impulses for operating said line relays, a neutral relay at each station having an energizing circuit closed when .its corresponding polar line relay assumes either of its polar positions, other relay means at each station selectively controlled in accordance with thepolar position of its corresponding polar line relay only during the pick-up period of its corresponding neutral relay, whereby said stations are selectively divided 'into groups in accordance with a polar impulse applied to said line circuit, and selector means responsive to the further operation of the line relay only at a station selected by said polar impulse.

17. In combination, a line circuit interconnecting a control office and a plurality of stations, a polar line relay included in said linecircuit at each of said stations, means for impressing 'a plurality of impulses of selected polarities on said line circuit, means responsive to said impulses for operating said line relays, a neutral relay at each station having an energizing circuit closed when its corresponding polar line relay assumes either of its polar positions, station selecting means at each station selectively controlled in accordance with the polar position of its corresponding polar line relay only during the pickup period of its corresponding neutral relay, whereby said stations may be remotely selected over said line circuit, and selector means responsive to the operation of the line relay only at a selected station.

18. In combination, a line circuit interconnecting a plurality of stations, a polar line relay included in said line circuit at each of said stations, means for impressing a plurality of impulses of selected polarities on said line circuit, means responsive to said impulses for operating said'line relays, a neutral relay at each station having an energizing circuit closed when its corresponding polar line relay assumes either of its polar posi tions, station selecting means at each station selectively controlled in accordance with the polar position of its corresponding polar line relay during the time that said corresponding polar line relay assumes a polar position and said corresponding neutral relay has not yet responded, whereby said stations are selected in accordance with the polarity of impulses applied to said line circuit, and selector means responsive to the operation of the line relay only at a selected station.

19. In combination, a line circuit interconnecting a plurality of stations, a polar line relay included in said line circuit at each of' said stations, means for impressing a plurality of impulses of selected polarities on said line circuit, means responsive to said impulses foroperating said line relays, a neutral relay at each station having an energizing circuit closed when its corresponding polar line relay assumes either of its polar positions, other relay means at each station having an energizing circuit including a back contact of its corresponding neutral relay and a polar contact of its corresponding polar relay in one or the other of its polar positions as previously determined, whereby said stations are selectively divided into groups in accordance with the polarity of an impulse applied to said line circuit, and selector means responsive to the operation of the line relay only at a selected station.

20. In combination, a line circuit, means for selectively applying positive or negative energy to said line circuit, a pair of polar line relays each having contacts capable of assuming either of two positions in accordance with the polarity of the energy applied to said line circuit, a pair of neutral relays energizing circuits closed for each of, said neutral relays when the contacts of said polar relays assume either of their positions, relay means selectively controlled in accordance with the positions assumed by the contacts of said polar relays during the pick-up period of said neutral relays and selector means selectively controlled by said relay means to be responsive to the further operation of said line relays after said neutral relays are picked up.

21. In combination, a line circuit, means for selectively applying positive or negative potential to said line circuit, a plurality of polar line relays included in said line circuit each of said polar relays having contacts operable to either of two polar positions, a neutral relay for each of said line relays, an energizing circuit for each of said neutral relays closed whenever the contacts of its respective polar relay assume polar positions, and selector means for each of said polar line relays, certain of said selector means responding to their polar relays only when their contacts assume one polar position during the pick-up period of their neutral relays and certain other of said selector means responding to their polar relays only when their contacts assume the other polar position during the pick-up periods of their neutral relays, whereby said selector means may be selectively controlled in accordance withthe polarity of the potential placed on said line circuit. I

22. In a remote control system, a line circuit, means for energizing said line circuit witha plurality of different series of impulses having distinctive characters, a plurality of line relays for repeating the impulses of each series, a plurality of selector means, one for each of said line relays, means causing certain of said selector means to be responsive to its respective line relay during a particular one of said series of impulses only if the first impulse of that series is of a particular distinctive character, means causing certain other of said selector means to be responsive to its respective line relay during a particular one of said series of impulses only if the first impulse of that series is of another particular distinctive character, and means for preventing any response of said selector means to a series of impulses when the first impulse of the series is not of said particular character.

23. In a remote control system, a line circuit, code transmitting means for energizing said line circuit with any one of a plurality of different series of code combinations of impulses of selected characters, a plurality of step-by-step means each operated through a cycle of operation in response to a series of impulses only when the first element of the series is of a particular character, electro-responsive means responsive to succeeding code elements of said series only when said step-by-step means operates through a cycle of operation, and means preventing any operation of said step-by-step means by succeeding impulses of a series when the first element of said series is not of said particular character.

24. In a communication system for centralized trafiic control, a control office, switch control devices and signal control devices located at a plurality of field stations, a line circuit for connecting the control office to the several field stations, a series of stepping relays at each field station, a line relay in said line circuit for energizing said stepping relays sequentially, a. station conditioning relay at each field station responsive to the polarity of energization of said line circuit for determining whether or not said bank of stepping relays shall be operated by subsequent operations of said line relay, a manually operable means for each station, means controlled by said manually operable means for determining the polarity of energization of said line circuit at a predetermined time to cause energization of said station conditioning relay and operation of the bank of stepping relays at that particular station, and control circuits for said switch and signal control devices governed by said stepping relays.

25. In a communication system for centralized trafiic control, a stepping line circuit extending from a control office to a field station, a line relay in said line circuit at the field station, a plurality of stepping relays at the field station, circuits controlled by said line relay for energizing said stepping relays sequentially one at a time, means at the station responsive to the polarity of energization of said line circuit at a particular time for determining whether or not said stepping relays shall be operated by subsequent impulses on said stepping circuit, and manually controllab le means in said control ofilce for determining the polarity of said energization of the line circult to cause operation of said stepping relays depending upon the condition of said manually controllable means. r

26. In a communication system'for centralized trafiic control, a stepping line circuit extending from a control ofiice to a field station, a line relay in said line circuit at the field station, a plurality of stepping relays at the field station, circuits controlled by said line relay for energizing said stepping relays sequentially one at a time, means at the station responsive to the polarity of energizationof saidline circuit at a particular time for determining whether or not said stepping relays shall be operated by subsequent impulses on said stepping circuit, manually controllable means in said control ofiice for determining the polarity of said energization of the line circuit to cause operation of said stepping relays depending upon the condition of said manually controllable means, and control relays at the field station for governing the operation of traffic controlling devices and having circuits selectively controlled by said stepping relays.

27. In a remote control system of the synchronous selector type; a stepping circuit; means applying a series of impulses to said stepping circuit; means selectively determining the character of each impulse of said series of impulses; a line relay in said stepping circuit distinctively responsive to each impulse of said series of impulses in accordance with the character thereof; a slowacting relay controlled by a, distinctive operation of said line relay, said slow-acting relay being picked up at the beginning of said series of said impulse and dropped at the end of said series of impulses; and a stepping relay bank initially controlled by the response of said line relay to an impulse of a distinctive character and said slowacting relay in its de-energized position, said stepping relay bank being selectively responsive to the distinctive operation of said line relay by a particular impulse of said series whereby said bank thereafter responds or fails to respond to all other operations of said line relay by said series of impulses.

28. In a remote control system of the synchronous selector type; a stepping circuit; means applying a series of impulses to said stepping circuit; means selectively determining the character of the first impulse of said series of impulses; a

line relay in said stepping circuit distinctively responsive to each impulse of said series of impulses in accordance with the character thereof; a slow-acting relay controlled by said line relay, said slow-acting relay being picked up at the beginning of said series of impulses and dropped out at the end of said series of impulses; and a stepping relay bank initially controlled by the response of said line relay to the first impulse of a distinctive character and said slow-acting relay in its de-energized position, said stepping relay bank being selectively responsive to the distinctive operation of said line relay by the first impulse of said series whereby said bank thereafter responds or fails to respond to all other operations of said line relayby said series of impulses.

29. In combination with a control relay, a selector of the relay type adapted to be operated by said control relay and comprising a series of counting relays interconnected to permit successive energization of the relays; a pick-up circuit for each said counting relay including a contact of the control relay, a front contact of the next preceding counting relay and a back contact of the second preceding counting relay; and means efiective when each counting relay becomes energized and including a back contact of such energized relay for releasing the next preceding relay.

30. In combination with a control relay, a selector of the relay type adapted to be operated by said control relay and comprising a plurality of counting relays arranged in order; a pick-up circuit for each odd-numbered counting relay including a front contact of the next preceding counting relay, a'back contact of the second preceding counting relay and a contact of said control relay closed in oneposition; a pick-up circuit for each even-numbered counting relay including a front contact of the next preceding counting relay, a back contact of the second preceding counting relay and a contact of :said control relay closed in another position; and a stick circuit for each counting relay including a back contact of the .next succeeding counting relay.

31. A selector of the counting relay type comprising a series of counting relays interconnected to permit successive energization of the relays, a

counting relay, and a holdinglcircuit for each said counting relay including its own front contact and a back contact of the next succeeding counting relay, a control relaygoverned from a distant point and provided with contacts which are al ternately closed, one contact of said control relay being included in the pick-up circuit for each odd-numbered counting-relay, and another contact of said-control relay'being included in the pick-up circuit for each even-numbered counting relay.

ROBERT M. PHINNEY. 

